1. Data are presented on the relation of the acid-base balance of the ration to the effects of elementary sulphur on food utilization and the well-being of rats. 2. The efficiency quotient on the base-forming rations was significantly better than on the acid-forming ones, and the addition of
elementary sulphur to these rations significantly lowered the efficiency index on both base- and acid-forming diets. 3. The efficiency quotient of the males was superior to that of the females. 4. No interaction between diets or between sex and diets appeared to be significant. 5. No pathological changes could be found in the livers of rats fed the various acid- and base-forming rations no matter whether they were supplemented with elementary sulphur or not.